It looks good as is. Not every surface needs to be decorated. Whatever you put there will compete with the pretty stained glass. You already have a bunch of objects by the sink; that is enough decoration.

Someone will probably suggest a wall clock. But don't you already have a clock on the oven and the microwave? Again, leave the space plain.

I’d continue the subway tile above the window; especially because you have that piece of crown molding to edge it. It would look complete and symmetrical with the cabinets.

Bigger window.

Consider backlighting the stained glass and hang it above the window. Then you get your view and the glass.